Dirty little Electron secret tanks macOS 26 performance

The Electron team has fixed code that caused system-wide slowdowns on the newly released macOS 26 "Tahoe."

Electron is a widely used framework for creating cross-platform applications using web technology. Applications using Electron include Microsoft's Visual Studio Code, pgAdmin for PostgreSQL management, Podman Desktop, Slack, Cursor, AWS Kiro, Theia IDE, and many more.

A fix committed last week removed an override of a private method in the Cocoa API, called _cornerMask. According to the author of the fix, the method calculates the shadow of the window, and overriding it "forces WindowServer to repeatedly recalculate and repaint the shadow." The likely reason the problem appeared only after the release of Tahoe is a new optimization, which this override then broke.

In Apple's naming conventions, methods starting with an underscore character are private and not intended for external ...